An excerpt from
Into the Cool
Energy Flow, Thermodynamics, and Life
Eric D. Schneider and Dorion Sagan
Introduction: Trouble at the EPA
Energy is the only life.—William Blake
Confessions of a Government Worker
In 1971 one of us, Eric Schneider, was haunted by two simple questions: Do laws exist that govern the behavior of whole ecosystems? If so, what are they?
At the time there may have been no one in the world for whom an answer to these questions would have proved more useful. As the director of the National Marine Water Quality Laboratory of the Environmental Protection Agency (EPA) in Narragansett, Rhode Island, Eric's mission was to provide scientific data to protect coastal water quality and estuaries. U.S. water-quality laws specifically gave the EPA the responsibility of protecting human health, commercial fisheries, and ecosystems within these coastal waters. Eric was expected to measure the health of ecosystems without definitions of ecosystem health and without adequate measuring tools. It was a difficult job.
Upon his arrival in 1971 as a new director at the EPA laboratory, Eric found that most of the data from the facility consisted of very simple toxicity tests done on algae and small fish. In a typical protocol, adults of the small bait fish mummichog (Fundulus heteroclitus) were submitted to toxins until measurable percentages of them died. Numerous tests were administered on organisms such as these that "kept well." Not to put too fine a point on it (and the EPA didn't), the organisms selected were those that could survive alone in aerated pickle jars. The EPA experiments were completed within ninety-six hours, a four-day span that allowed them to be set up and dismantled within a government workweek. If not rigorously scientific, the protocol was bureaucratically convenient. The main problem is that such tough species are not necessarily representative of the health of their surrounding ecosystems. For example, some of the hardiest organisms belong to pioneer species that repopulate damaged ecosystems. Such organisms thus may signify not health but ecosystem illness. Counting how many members of a poisoned tough species died in aerated pickle jars within ninety-six hours: such was the basis of our national water-quality standards throughout the 1960s and the early 1970s.
Even though Eric's expertise was not in biology—he had graduated with a doctorate in marine geology from Columbia—it seemed clear to him that the laboratory's task should not be to protect just hardy bait fish dosed with high levels of poisons. It should, rather, be to protect whole marine ecosystems. What good was it, he reasoned, to develop a water-quality standard for a species of fish if the organisms they ate were poisoned to death at much lower toxin concentrations? What if the lives of these tough guys depended on those of weaker, more easily poisoned beings? If that were the case, then the hardy beings could be tough today and gone tomorrow. In truth, very little seemed known about the linkages among species. Weren't members of healthy ecosystems, like happy people, well connected to a vibrant, interdependent community of other beings?
When Schneider asked coworkers the obvious—why they were not testing whole ecosystems—they made comments such as, "You cannot bring a whole ecosystem into the laboratory." Or they would say, "You cannot replicate a natural system in the laboratory."
Nonetheless, a few years later, these same researchers did just that: they studied, in careful miniature, whole marine ecosystems. The scaled-down ecosystems, or mesocosms (middle-sized worlds) as they were called, were miniature versions of the Narragansett Bay. The interdependent systems consisted of many representative species living in seawater that filtered into tanks from outside the Rhode Island EPA laboratory. And they mimicked the real bay ecosystems with amazing accuracy. But it still remained nearly impossible to carry out toxicity experiments in the natural environment: understandably, the EPA and the state pollution-control officials were against spreading toxins such as mercury in the oceans or in natural salt marshes, even for the loftiest of scientific purposes. At the same time, "naturally" polluted areas such as oil spills or areas poisoned by mercury from paper production became makeshift laboratories where scientists attempted to gauge the movement of toxic materials and the recovery, if any, of damaged ecosystems. To make a long story short, in 1971 it became clear to Eric that ecosystem toxicology—a subdiscipline of ecology, and the science the EPA needed if it was to protect the environment—was in its infancy. And this held true of ecology in general. Although human habitats were increasingly endangered, the science required to understand exactly how they became endangered—and thus how they could recover—barely existed.
Since then ecology has made great progress. Ecologists study the interactions that determine the distribution and abundance of organisms. Most of what we know about this comes from hundreds of years of careful observations of changes in species, populations, and landscapes. Only in the last 150 years have these observations begun to be organized. Ecology branched out into many specialized theories: today there is population-abundance theory, predator-prey theory, niche theory, autecology, synecology, ecosystems ecology, microecology, ant ecology, human ecology, elephant ecology, as well as lots and lots of modeling. But where, Eric wondered, was the general theory that could predict actual whole ecosystem behavior? Where was the theory that would say what would happen to a given lake ecosystem if its ambient temperature were increased by 5°C? How about if this ecosystem became more acidic? What would happen then? And what would another ecosystem, with different organisms, do under the same conditions? Marine chemists had found that pollutants such as DDT, radioactive elements, and mercury were moving through the global ecosystem and taking their ecological and human toll. But what routes did these toxic materials take, what were their rates of movement, and where did similar materials accumulate in natural systems? It seemed to Eric that what the EPA really needed was a theory that explained the flow of material and energy through whole ecosystems.
Perhaps due to his training in the physical sciences, Eric was attuned to look for patterns and laws that might apply across the board, to all ecosystems. In particular, he was drawn to investigations by earlier researchers on energy flow. Might simple physical principles underlie the complexity of biology, from ecosystems to the biosphere? The relevant researchers seemed to be at least trying to deal with whole ecosystems rather than with their constituent parts. There were a few groups, mostly the students and graduate students of G. Evelyn Hutchinson at Yale University, who had made significant inroads in tracking energy's flow through, and effect upon, whole ecosystems. Hutchinson and his colleagues, first at the Cold Spring Harbor Symposium on Quantitative Biology in 1957, and later at the Brookhaven Symposium on Diversity and Stability in Ecological Systems, raised ecology's sights beyond a narrow focus on the distribution and abundance of individual species. The insights of Hutchinson and his colleagues led beyond the quantification of interacting nutrients and their effects. It was to lead Eric Schneider and a few others to the bigger question of why ecosystems behave as they do, a question directly related to the fascinating question—some would say the question of questions—of why (from a material and physical perspective) life exists.
The answer had to do with energy, and it would eventually shed light not only on ecosystems, but also on organisms and nonliving systems—the entire field of what has come to be called the sciences of complexity. Indeed, as Eric was to find out with delight and surprise, he was not alone: a most promising research program linking biology to the physics of energy was already under way. It was like finding a buried treasure: gems lingered in past theoretical work, and the energy-flow characteristics of a handful of ecosystems had already been enumerated. To his great excitement, Eric found out that there was already a young but sophisticated science of thermodynamics that specifically studies energy flow and transformations in natural systems.
S S S
Even in the beginning of thermodynamics—the science of heat's movements and energy's transformations—Ludwig Boltzmann, one of the science's founders, had important things to say about life. Scientifically speaking, life can be regarded as one of a class of complex systems ruled by energy and its transformations. As the backbone of energy flow and chemical kinetics, thermodynamics is crucial to understanding life. Theoreticians who want to understand energy flow and transformations in biology must look the science of thermodynamics in the eye, as any theoretical claim is meaningless unless it conforms to thermodynamic principles. As Eric would learn, this obscure science, which started with efforts to develop more efficient steam engines, was absolutely required to understand life. Today the sciences of energy flow that began with thermodynamics shed light on how organisms grow and develop, on the origin and history of early life, on ecosystem development and how people might live more sustainably on the Earth. Eric's search for the underlying physical principles of ecosystems became part of a whole new science, the thermodynamics of biology. Not only has this emerging science generated its share of hypotheses and ideas, but some of these ideas have been and are being confirmed using previously accumulated ecosystem data. And one of the most interesting ideas of this new science concerns not only how life is organized by energy flow, but the material reason for its existence.
The New Thermodynamics
Thermodynamics, often considered boring and irrelevant—a gray mathematical wasteland of steam tables and arcane verbiage, important perhaps for laboratory measurement of molecules, for creationists or Victorian historians, but of no concern to the ordinary scientist or person—turns out to be a most fascinating field. It bears directly on our deepest understanding of life and its operations. Among those who have developed, clarified, and tried to improve upon the foundations of classical thermodynamics are some of the greatest names in the history of science: Carnot, Clausius, Boltzmann, Gibbs, Maxwell, Planck, and Einstein. But theirs was a thermodynamics of equilibrium systems—systems that were boring, because they were headed toward stasis, an end state where nothing (or at least nothing of interest) happened. "Heaven is a place," David Byrne sings, "where nothing ever happens." Indeed, the initial investigations of thermodynamics were prematurely extrapolated to the entire universe to predict an end state more boring than heaven, colder than hell—a nonmystical apocalypse more meaningless than the most pessimistic fantasy of the most depressed philosopher. This foregone scientific conclusion was called the "heat death" of the universe.
One nineteenth-century book showed a white-haired man gazing out in wide-eyed horror at the ocean, which had frozen, in midwave. A dying sun, and an ocean of solid ice: such were the inevitable conclusions of the great new discipline whose subject was energy—how to extract it, how to understand it, and how to deploy it in engines of steam to gain the national upper hand. "This is the way the world ends, not with a bang but a whimper," wrote poet T. S. Eliot. The poor universe would come to a standstill so complete that no ember or hope remained of it ever rising, phoenixlike, from its own ashes. In the frame of this last judgment pronounced by science, this atomic chaos without recompense, human striving looked ridiculous—and here the heat death perhaps provided secret sustenance for European philosophies of existentialism and nihilism, and for the aesthetics of the theater of the absurd under writers such as Harold Pinter and Samuel Beckett. Like frantic ants so easily trampled, our piddling lives were ultimately ludicrous in their vanity. However civilized we were, however much we might evolve, this was so. The devout of previous centuries, such as William Buckland, had profusely thanked the providence with which the deity had deigned to lace Great Britain with abundant reserves of coal, that energetic fount of the industrial revolution and global dominion, ensuring English hegemony with God's divine favor. But later minds of a more scientific bent could not be so sure. Life seemed the supreme accident, some sort of cosmic fluke. All organization, including that of Earth, was on its way out. Life either would never last or, as the creationists liked to argue (and some still do), life was divinely ensouled, crafted, and cared for in a universe otherwise thermodynamically destined for unrecoverable destruction. And science—thermodynamics—had proved it.
Well, not so fast. Far from predicting cosmic burnout, modern thermodynamics shows how complex structures, living or not, often come into being, expand, and increase their complexity in regions of the universe exposed to energy flow; because the interaction of the fundamental forces of the universe (gravity, electromagnetism, the weak and strong nuclear forces) are not completely integrated, nor the total matter of the universe known, guarantees of a heat death (or even an end) are not scientifically credible. This book focuses on how thermodynamics has evolved over the past fifty years to allow for the study of a new class of thermodynamic systems known as nonequilibrium or dissipative systems because they exist some distance away from equilibrium. The structures studied by this science include thunderheads, whirlpools, intricate chemical cycles, and life. The proponents of this new, expanded thermodynamics include names for the most part less well known than the founders of the field, scientific stars such as Alfred Lotka, Lars Onsager, Erwin Schrödinger, Ilya Prigogine, George Hatsopoulos, Joseph Keenan, Joseph Kestin, Don Mikulecky, and Jeffrey Wicken. Upon the shoulders of these giants, thermodynamics has been both broadened—it now applies neatly to life as well as to mechanical devices—and simplified. Most exciting to us is the major simplification we show that "nature abhors a gradient" (Schneider and Kay 1989; Sagan and Schneider 2000). This surprisingly fruitful concept, which we present in detail, condenses much of the recent work in thermodynamics.
This idea that nature abhors a gradient, one of the key ideas of this book, is very simple: A gradient is simply a difference (for example, in temperature, pressure, or chemical concentration) across a distance. Nature's abhorrence of gradients means that they will tend spontaneously to be eliminated—most spectacularly by complex, growing systems. The simple concept of collapsing gradients encapsulates the difficult science of thermodynamics, demystifies entropy (as important to the universe as gravity), and illuminates how all complex structures and processes, including those of life, come naturally into being.
We are familiar with nature's breakdown of gradients in one case. Nature abhors a vacuum, and will spontaneously crush a metal can from which the air has been removed. In this example, nature, without prompting or design, rectifies the pressure difference between the low pressure inside and the high pressure (fourteen pounds per square inch) outside of the can. But in this book we vastly extend the pressure example. We show that nature's abhorrence of this and many other gradients is a law of nature, an unstoppable tendency where energy flow leads to different natural complex systems including life itself. We show the great significance of this law (called the second law of thermodynamics) for the origin, persistence, and eventual demise of complex natural systems even such as the nation-state. We trace the history of scientific thought on energy and matter to where we are: on the eve of a great unification of the sciences. Energy from the sun generates, perpetuates, and elaborates new identities, from whirlwinds and flowers to economies and governments, many of which seem as if they were planned by an invisible hand or eye.
Indeed, life's emergence and evolution is, we argue, a cyclical process sired by energy flow. Although life is safeguarded by the natural biotechnology of DNA replication, and spread by reproducing cells, it is energy that gives the evolutionary process its impetus to begin and persist. Complex patterns of cycling matter appear in regions of energy flow. Life, from its inconspicuous microscopic start to its possible interplanetary and interstellar future, is one of these patterns.
Life as a Manifestation of the Second Law
The classical students of thermodynamics recognized both the power and limitations of their science. They knew that they lived in a world quite separate from the highly idealized systems where maximum entropy and disorder reigned. Nowhere was this apparent conflict so dramatic as when one compared evolving life to the prediction that random processes would lead to the heat death of the universe. The second law in its original formulation foretold things inexorably losing their ability to do work, burning out and fading away until all states are in or near equilibrium with no energy left to run organisms or machines. But life demonstrates an opposite, evolutionary tendency, of complexity increasing with time.
How? This was the heart of the paradox. In this book we call it the Schrödinger paradox after the quantum physicist who first focused on the need to explain life's apparent defiance of the second law of thermodynamics. The second law, in its basic original form, states that entropy (atomic or molecular randomness) will inevitably increase in any sealed system. Yet living beings preserve and even elaborate exquisite atomic and molecular patterns over eons.
Eric Schneider had begun a mission, a scientific quest for biological-ecological bedrock. Acquainting himself with the energy ecologists, he looked for the ecological equivalent of Newton's laws, the F = ma (force = mass × acceleration) of physics. Where were the simple equations such as those that describe transport in fluids (the so-called Navier-Stokes equations) for ecosystems? Did they even exist? At first it seemed they might not. Yet the search for them, detailed in Erwin Schrödinger's famous 1944 book, What Is Life? certainly did. The three lectures upon which Schrödinger's book was based outlined two future sciences: the molecular biology that has proved to be such a force in the world, and the thermodynamics of biology that has yet to prove its mettle. Schrödinger's second subject is the topic of the present book. Into the Cool should be considered a journey into the heart of an emerging science that combines life with physics in a mix that may some day be as potent as molecular biology and as practical as biotechnology. In this book we test our "biothermodynamic" thoughts against the data and extend them into economics, human health, the sustainability of ecosystems, and the possibility of life in outer space.
In the end several philosophical issues are thrust upon us. Foremost among these is the question of life's existence. Why life? Does life, scientifically viewed, have an overall function? Our answer is yes. A barometric pressure gradient in the atmosphere, the difference between high- and low-pressure masses, leads to a tornado, a complex cycling system. The tornado's function, its purpose, is to eliminate the gradient. Life has a similar natural purpose. Only instead of quickly destroying a pressure gradient and then disappearing, it tends to reduce, over billions of years, the huge solar gradient between hot sun and cold space, growing in complexity as it does so. The growth of complex, intelligent life can be directly traced to the effectiveness of life as a cycling material system adept at reducing gradients. The original and basic function of life, as of the other complex systems that we examine in this book, is to reduce an ambient gradient.
Culture critic C. P. Snow, disapproving the increasing gap between the sciences and the arts, suggested that any educated person should know the second law of thermodynamics. Not knowing the second law was, he said in his Two Cultures and a Second Look (1969)—an early warning shot in the ever-changing battlefield of the culture wars—equivalent to not having read a work by Shakespeare. The second law is neither a guarantor of cosmic death nor an arcane mathematical equation of interest only to polymer chemists. Rather, the second law helps explain the creation and elaboration of complex systems run by energy flow. The second law also directs our attention toward the directional processes we see in many sorts of developing complex systems, including those of our own evolution. In short, the natural phenomena described under the rubric of the second law not only destroy, but create—by destroying gradients.